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The season consisted of six serials and thirteen episodes. With this season the BBC experimented with the format of the series, reducing the number of episodes to thirteen, but making each episode forty-five minutes long. The experiment did not result in improved ratings and at the end of the season the BBC announced it was cancelling the series; uproar from fans resulted in the BBC changing its mind and putting the series on an eighteen-month hiatus instead. This season is notable for featuring the final appearance of Patrick Troughton as the beloved Second Doctor, in a storyline that gave rise to a popular fan theory known as Season 6B.

Contrary to common belief, season 10 kicked off in the last week of December 1972 — not in 1973, as would be expected. Season 10 actually began nine years after season 1 started. In fact, The Three Doctors began nine years to the week after The Daleks first aired.

For the purposes of this list, "Series 4" is considered to be the production series 4, which ran all the way from Time Crash to The End of Time.

The years seen in this section may seem decidedly "off". Remember, however, that this list only gives the first year in which an episode from a series was broadcast. David Tennant, unusual amongst other Doctors, began and ended on special episodes, not regular ones. Thus, his series actually begin in 2005, 2006 and 2007 — not 2006, 2007 and 2008 as is commonly thought.